Is my PC running the 32-bit or 64-bit version of Windows?

Applies to these editions of Windows 7

The terms 32-bit and 64-bit refer to the way a computer's processor (also called a CPU), handles information. The 64-bit version of Windows handles large amounts of random access memory (RAM) more effectively than the 32-bit version.
Follow the steps in the sections below to find out if your PC is running the 32-bit or 64-bit version of Windows and what edition of Windows is on your PC.

Computers running Windows XP

Click Start, right-click My Computer, and then click Properties.

If "x64 Edition" is listed under System, you’re running the 64-bit version of Windows XP.

If you don’t see "x64 Edition" listed under System, you’re running the 32-bit version of Windows XP.

The edition of Windows XP you're running is displayed under System near the top of the window.